- Clinical science
Hypogonadism is a clinical syndrome associated with impaired functional activity of the gonads. Both males and females can be affected. It is classified as either primary or secondary: Primary hypogonadism (hypergonadotropic hypogonadism) is typically caused by congenital disorders of sex development affecting the gonads (e.g., Turner syndrome, Klinefelter syndrome) or acquired gonadal injury (e.g., irradiation, infection). Secondary hypogonadism (hypogonadotropic hypogonadism) is most often caused by pituitary or hypothalamic disorders (e.g, craniopharyngioma, Kallmann syndrome). Characteristic features in males include testicular hypoplasia, gynecomastia, and absent facial hair growth, while females commonly present with amenorrhea. Following clinical evaluation, the diagnosis is confirmed with hormone tests, and genetic testing may be considered. Treatment involves management of the underlying cause and hormone replacement therapy.
Hypogonadism is a clinical syndrome associated with impaired functional activity of the gonads.
- Definition: insufficient sex steroid production in the gonads
- Primary gonadal insufficiency; : ; (females), (males), androgen insensitivity syndrome, anorchia
- Secondary gonadal insufficiency (damage to leydig cells or ovarian tissue): chemotherapy, pelvic irradiation, trauma/surgery, autoimmune disease, infections (mumps, tuberculosis)
- Definition: insufficient gonadotropin-releasing hormone (GnRH) and/or gonadotropin release at the hypothalamic-pituitary axis
- Genetic disorders
- Hypothalamic and/or pituitary lesions due to
- Eating disorders ( )
- Hypergonadotropic hypogonadism: gonadal insufficiency; → insufficient sex steroid production (↓ testosterone, ↓ estrogen) → increased gonadotropin secretion (↑ FSH and ↑ LH) from the anterior pituitary → lack of negative feedback; from the impaired gonads → further ↑ FSH and ↑ LH levels
- Hypogonadotropic hypogonadism
- (see )
- Developmental abnormalities with genitalia (undescended testes, hypospadias)
- Infertility (↓ sperm count), impotence, and/or ↓ libido
- Examine patient for features of:
- ↓ Serum testosterone levels (in males; usually < 300 ng/dL) and ↓ serum estrogen levels (in females)
- Determine if the source is primary or secondary hypogonadism.
- Bone scan may support the diagnosis of hypogonadism (↓ bone density (osteoporosis ) or delayed epiphyseal closure).
Further tests: based on suspected etiology
- Genetic testing (for Klinefelter syndrome, Turner syndrome, Kallmann syndrome)
- Serum prolactin (↑ in prolactinoma)
- Pelvic ultrasound (e.g., gonadal dysgenesis in Klinefelter syndrome)
- Brain MRI (for CNS lesion or Kallmann syndrome )
- Adrenocorticotropic hormone stimulation test ( ): to exclude congenital adrenal hyperplasia
- Treat underlying cause: e.g., surgical excision of tumors, pharmacotherapy for prolactinomas
Hormone replacement therapy
- Trigger onset of puberty in prepubertal individuals at appropriate age
- To improve fertility in postpubertal individuals with hypogonadotropic hypogonadism and, if prepubescent, an alternative to triggering onset of puberty and growth